Bean control system for an LED luminaire

ABSTRACT

Described are an improved automated multi source luminaire and luminaire systems. More particularly a multicolor LED array luminaire system with a series of lenses and light louvers to control the light beam.

RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 13/018,203 filed Jan. 31, 2011 by Pavel Jurik, et al. entitled“Beam Control System for an LED Luminaire”, now U.S. Pat. No. 8,496,354,issued on Jul. 30, 2013, which claims priority to U.S. ProvisionalApplication No. 61/417,194 filed on Nov. 24, 2010 by Pavel Jurik, et al.entitled, “Beam Control for an LED Luminaire”.

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a method for controlling thelight output from an array of LEDs when used in a light beam producingluminaire, specifically to a method relating to preventing spill lightand/or for controlling the beam angle of the array.

BACKGROUND OF THE INVENTION

High power LEDs are commonly used in luminaires—for example in thearchitectural lighting industry in stores, offices and businesses aswell as in the entertainment industry in theatres, television studios,concerts, theme parks, night clubs and other venues. These LEDs are alsobeing utilized in automated lighting luminaires with automated andremotely controllable functionality. For color control it is common touse an array of LEDs of different colors. For example a commonconfiguration is to use a mix of Red, Green and Blue LEDs. Thisconfiguration allows the user to create the color they desire byadditively mixing appropriate levels of the three colors. For exampleilluminating the Red and Green LEDs while leaving the Blue extinguishedwill result in an output that appears Yellow. Similarly Red and Bluewill result in Magenta, and Blue and Green will result in Cyan. Byjudicious control of these three controls the user may achieve any colorthey desire within a color gamut. More than three colors may also beused and it is well known to add an Amber or White LED to the Red, Greenand Blue to enhance the color mixing and improve the gamut of colorsavailable.

The differently colored LEDs may be arranged in an array in theluminaire where there is physical separation between each LED, and thisseparation, coupled with differences in die size and placement for eachcolor, may affect the spread of the individual colors and results inobjectionable spill light and/or color fringing of the combined mixedcolor output beam. It is common to use a zoom lens or other opticaldevice in front of each LED to allow the user to control the beam shapeand angle of the output beam; however these optical devices commonlyhave differing effect for different colors and color fringing or otheraberrations may be visible in the output beam. It would be advantageousto have a system where the beam angle is remotely variable and wherestray light and aberrations are well controlled.

There is a need for a beam control system for an LED array basedluminaire which can be remotely variable and provide improvements inspill light reduction and beam angle control.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings in which likereference numerals indicate like features and wherein:

FIG. 1 illustrates a prior art system;

FIG. 2 illustrates a typical automated lighting system;

FIG. 3 illustrates an embodiment of the invention;

FIG. 4 illustrates a cut-away view of components of the embodiment ofthe invention illustrated in FIG. 3;

FIG. 5 illustrates a small louver mask of an embodiment of theinvention;

FIG. 6 illustrates a large louver mask of an embodiment of theinvention;

FIG. 7 illustrates a single module of the embodiment of the inventionillustrated in FIG. 3;

FIG. 8 illustrates a single module of an alternative embodiment of theinvention;

FIG. 9 illustrates a cut-away view of an embodiment of the invention;

FIG. 10 illustrates a side cross-sectional view of an embodiment of theinvention;

FIG. 11 illustrates the CIE 1931 chromaticity space with Planckianlocus; and

FIG. 12 illustrates strobe and control zones of an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are illustrated in theFIGUREs, like numerals being used to refer to like and correspondingparts of the various drawings.

The present invention generally relates to a method for controlling thelight output from an array of LEDs when used in a light beam producingluminaire, specifically to a method relating to preventing spill lightand for controlling the beam angle of the array.

FIG. 1 illustrates a prior art system showing two LEDs as may be used ina luminaire. LED 102 and LED 104 may be of differing colors and, due tothe different optical properties and construction of the LED dies,respectively produce light beams 106 and 110. These beams may differ inbeam spread and position. These differences result in light beams fromLEDs 102 and 104 impinging on an illuminated object 118 in such a waythat areas 114 and 116 of the object are illuminated by a single LEDonly rather than the desired mix of both. This results in areas 114 and116 being colored differently from the central mixed area and appearingas colored fringes. Only Two (2) LEDs are illustrated in FIG. 1 forclarity and simplicity. It should be appreciated that the same problemexists with systems incorporating more than two colors of LED. Inaddition to multiple colors of LEDs the luminaire may incorporatemultiple sets of luminaires and the spacing between the LEDs and sets ofLED's may vary within a single luminaire or in different luminairedesigns.

FIG. 2 illustrates a typical multiparameter automated LED luminairesystem 10 which may incorporate the invention. These systems commonlyinclude a plurality of multiparameter automated luminaires 12 whichtypically each contain on-board an array of LEDs, and electric motorscoupled to mechanical drives systems and control electronics (notshown). In addition to being connected to mains power either directly orthrough a power distribution system (not shown), each luminaire isconnected is series or in parallel to data link 14 to one or morecontrol desk(s) 15. The luminaire system 10 is typically controlled byan operator through the control desk 15. Consequently, to affect thiscontrol, both the control desk 10 and the individual luminairestypically include electronic circuitry as part of the electromechanicalcontrol system for controlling the automated lighting parameters.

FIG. 3 illustrates an automated luminaire embodiment of the invention.Luminaire 100 contains multiple LED modules each of which is fitted withprimary optics, first and second micro lens arrays and relatively small120 and large 124 louver masks. Different louver masks 120 and 124 mayhave different heights and width louvers array. By changing the louvermasks to ones with different heights of louver array the user maycontrol the beam angle, stray light and color fringing of the luminairein addition to that control provided by the variable focal length microlens arrays system described in greater detail below. Louver mask arrays120 and 124 may further provide mechanical protection and dust exclusionfor the micro lens arrays and LED modules.

FIG. 4 illustrates a cut-away view of assembled light path components ofa embodiment of the dual louvered LED arrays from the automatedluminaire 100 of FIG. 1. From left to right individual LED module(s) 106is/are paired with primary optic(s) 126, which in turn is/are pairedwith a first micro lens array 122, which in turn is paired with a secondmicro lens array 123, which in turn is paired with small louver arraymask 120, which in turn is paired with large louver mask 134. In theembodiment illustrated in FIG. 4, the LED modules 106 are configured inan array and the large louver masks 134 also forms an array 124 whereeach LED Module 106 is paired a large louver mask 134 in the largelouver mask array 124.

In various embodiments Each LED module 106 may comprise a single LED dieof a single color or a group of LED dies of the same or differingcolors. For example in one embodiment LED 106 comprises one each of aRed, Green, Blue and White die. In some embodiments these LED die(s) maybe paired with optical lens element(s) as part of the LED module. Thoughthe LED modules 106 shown are illustrated as individual pieces, invarious embodiments these modules 106 may set out in an array ofmultiple modules as a one piece or multiple pieces. Similarly theprimary optics 126 are illustrated as one piece per LED module. In otherembodiments the primary optics may be configured in an array of multipleprimary optics to be paired with an array of multiple LED modules.Likewise the first micro lens arrays 122 are illustrated as individualpieces. In other embodiments the first micro lens arrays 122 may be partof a larger array to be paired with an array of multiple LED modules.

FIG. 5 illustrates a small louver mask array of an embodiment of theinvention. Louver mask 120 contains multiple cells 132 each of which maybe aligned with a single lens 142 of second micro lens array 123 asillustrated in FIG. 7 and FIG. 8. The illustrated louver mask utilizeshexagonal cells 132 however in other embodiments the cells may make upany shape such as round, triangular, square, or other shape(s). In theembodiment shown, the small louver mask array is shown as a piece for asingle LED module 106 (not shown in this figure). In other embodimentswhere there is an array of LED modules 106, the small louver mask arraysmay in turn be configured as an array of small louver masks to be pairedwith an array of LED modules 106. In other embodiments the small louvermask may be a single part that covers multiple LED modules 106.

In one embodiment of the invention every louver mask 120 on each modulein the luminaire is identical and every cell 132 within those masks isalso identical but in further embodiments the louver masks 120 or cells132 may differ within a single module or between different modulesacross the luminaire. In yet further embodiments the height of louvermask array 120 may be varied to effect different controlled beam anglesfor the emitted light. Such combinations of differing optical elementsand louver array height may be advantageously chosen so as to allow finecontrol of the beam shape and quality. The louver mask arrays reducecolor fringing or halation and control the beam angle to provide thelighting designer with a well controlled and defined beam of a singlehomogeneous color.

FIG. 6 illustrates the large louver masks array 124 of the embodiment ofthe invention illustrated in FIG. 3 and FIG. 4. Louver mask array 124contains multiple cells 134 each of which may be aligned with an LEDmodule 106 (not shown in FIG. 6) and its associated primary optic 126(not shown in FIG. 6), first 122 (not shown in FIG. 6) and second microlens array 123 (not shown in FIG. 6) and first, small, louver mask 120(not shown in FIG. 6). The illustrated louver mask utilizes round cells134 however in other embodiment other cell shapes may be employed.

In one embodiment of the invention every louver mask cell 134 isidentical but in further embodiments the louver mask cells 134 maydiffer at different positions across the array. In yet furtherembodiments the height of cells 134 of louver mask array 124 may bevaried to effect different controlled beam angles for the emitted light.Such combinations of differing optical elements and louver array heightmay be advantageously chosen so as to allow fine control of the beamshape and quality.

FIGS. 7 and 8 illustrate operation of the various optical elements ofthe luminaire as they relate to a single LED module 106 of an embodimentof the invention in two different embodiments 103 and 105. The lightoutput from an LED module 106 which may contain multiple LEDs of thesame or differing colors enters primary optic 126. Primary optic 126provides beam collimation and may be a reflector or a lens utilizingtotal internal refection (TIR). After passing through and beingconstrained by primary optic 126 the light beam enters first and secondmicro lens arrays 122 and 123 comprised of micro lenses 144 and 142respectively. In the embodiment illustrated the first micro lens array122 is fixed in position relative to LED module 106 and primary optic126 while second micro lens array 123 is able to move 121 along orparallel to the optical axis 150 of the system. The two micro lensarrays 122 and 123 together form an optical system whose focal lengthmay be varied by moving second micro lens array 123 towards and awayfrom first micro lens array 122 as indicated by arrow 121. The microlenses in micro lens arrays 122 and 123 may both face in the samedirection as illustrated here or may face in opposing directions. Theuse of micro lens arrays as opposed to single larger lenses has a numberof advantages, including but not limited to:

-   -   a. Micro lens arrays may be significantly thinner than a single        lens of the same focal length and thus lighter and easier to        move.    -   b. Micro lens arrays may provide homogenization of the light        beam as well as altering the beam divergence.

In the present disclosed embodiment second micro lens array 123 isassociated with a first, small, louver mask 120 which may be attached tosecond micro lens 123 and will move along the optical axis with it.Small louver mask 120 may be in contact with second micro lens array 123in order to maximize the effectiveness and prevent any stray light frompassing underneath small louver mask 120. As the combination of secondmicro lens array 123 and associated small louver mask 120 traversesbackwards and forwards along or parallel to the optical axis 150 of theoptical system as indicated by arrow 121 the focal length of the opticalsystem formed by micro lens arrays 122 and 123 and primary optic 126will vary, and thus the divergence of the light beam exiting secondmicro lens array 123 will vary as it passes through small beam louver120. This resultant output beam is then further constrained by second,large, beam louver 124.

Large beam louver 124 may be in a fixed position relative to LED module106, primary optic 126 and first micro lens array 122 as shown withembodiment 103 as illustrated in FIG. 7 or may be allowed to traversealong the optical axis of the optical system in conjunction with smalllouver mask 120 and micro lens array 123 as shown with embodiment 105 asillustrated in FIG. 8 and indicated by arrow 121. In eitherconfiguration large beam louver 124 provides a further masking of anystray light from the variable focal length system and further serves toeliminate colored fringing from the light beam. An advantage of theembodiment illustrated in FIG. 7 is that the output louver 124 does notmove. The advantage of the embodiment illustrated in FIG. 8 is that thecontrolling effects of the louver are consistent throughout the range ofbeam angle control when it remains adjacent to the first louver maskarray 120. FIG. 9 illustrates that a final, third, overall louver mask125 may optionally be fitted to the luminaire. Such a louver mask iscommonly known in the art as a ‘top hat’ and, in the describedembodiments, will cooperate with the louver masks 120 and 124 to furthercontrol any remaining light spill from the luminaire. Optional louvermask 125 may advantageously be provided as a removable component suchthat the user may easily insert or remove it from the luminaire asdesired. Optional louver mask 125 may be of fixed height or may beadjustable. Optional louver mask 125 may advantageously benon-reflective so as to avoid spill light, this may be achieved bypainting or coating the louver mask with matte black paint, anodizing orother coating as known in the art.

It can be seen that changing the heights of one or both louver masks 120and 124 will alter the constrained beam angle of the output beam. Ataller louver will produce a narrower beam and a shorter louver willproduce a wider beam. The louver masks 120 and 124 may be of fixedheight or may be adjustable.

As previously described Louver masks 120 and/or 124 may benon-reflective so as to avoid spill light, this may be achieved bypainting or coating the louver mask with matte black paint, anodizing orother coating as known in the art.

The louver masks 120 and/or 124 may be made of a metal, plastic, glassor other suitable material. As previously discussed the materials mayhave effective transparency of zero percent (0%). In alternativeembodiments the louver 120 and/or 124 materials may have a non-zeropercent transparency between zero and approaching full transparency(0%<t<100%). In differing embodiments the materials can be clear ordeffuse or clear with defusing surface treatments. The effect ofnon-opaque louvers is to illuminate the space between the microlensarrays 123 and/or between the lenses 142 with in a single microlensarray 123 and thus fill with light these spaces resulting in decreasedappearance of pixellation of the fixtures.

LED module 106 may contain LEDs of a single color and type or ofmultiple colors. The invention is not limited by the number, colors, ortypes of LEDs used and is applicable with any layout of any number ofany type and any color of LEDs or OLEDs.

FIG. 10, an illustration of a side cross-sectional view of theembodiment detailed in FIG. 8. Louver masks 120 and 124 and second microlens array 123 are mounted to carrier 168 to be carried back and forthin direction(s) 167 increasing or decreasing there distance from firstmicro lens array 122 as further described below. Stepper motor linearactuators 162 and 163 are mounted to plate 166 which is fixed relativeto first micro lens array 122 and primary optic 126. The output rods 164and 165 of linear actuators 162 and 163 are connected to carrier 168. Asstepper motor linear actuators 162 and 163 are operated their respectiveoutput rods 164 and 165 will be extended or retracted, causing carrierplate 168 and attached louver masks 120 and 124 and second micro lensarray 123 to move away from or closer to first micro lens array 122 andprimary optic 126. Although two stepper motor linear actuators areherein illustrated the invention is not so limited and any number ofstepper motor linear actuators may be utilized. Stepper motor linearactuators 162 and 163 may be operated cooperatively and simultaneouslysuch that carrier 168 and its attached optical assembly remains parallelto plate 166 and its attached optical assembly.

FIG. 11 and FIG. 12 illustrate a further improvements of the previouslydescribed embodiments of an LED based luminaire related to adjusting thewhite light produced by suitable combinations of intensities of coloredlight from LED modules 106. For example red, green and blue LEDs may bemixed to form a white light by choosing appropriate levels for each ofthe three colors. The color temperature of the white light produced maybe selected from a range as illustrated by line 202 on the standard CIE1931 chromaticity space as illustrated in FIG. 11. The range of whitelight points of different color temperatures are shown on such a diagramby the curved line 202 is well known as the Planckian Locus or BlackBody Line. Specific points on the Planckian locus are defined by thecolor temperature at that point, where the color temperature is thetemperature in Kelvin (K) that a theoretically perfect black body wouldhave to be to emit the same radiation spectrum. For example, anincandescent lamp may have a color temperature of 3,200K which indicatesthat the white light radiation from it is the same as that emitted froma perfect black body heated to 3,200K. Color temperatures of white lightmay range from the very high, blue, end of the Planckian locus at10,000K or more down to the very low, red, end at 1,000K or less. As anincandescent lamp is dimmed from full output to blackout its colortemperature will drop and its color point will tend to move along thePlanckian locus. This is familiar as the well-known phenomenon of anincandescent lamp getting redder as it dims. For example a lamp whosecolor temperature is 5,600K (as shown by point 204 in FIG. 11) may bedimmed in output and its color temperature may drop to around 1,500K (asshown by point 206 in FIG. 11). Although LED emitters do not naturallyexhibit this phenomenon as they are dimmed, the described embodimentsimulates such a color temperature shift by continuously varying theintensity mix of colored light from LED modules 106 so as to producewhite light of the appropriate color temperature. Such a simulation inthe change of color temperature as the luminaire is dimmed allows theLED luminaire to emulate the appearance of an incandescent luminaire.The desired combinations of the colored LED emitters necessary toproduce white light of any required color temperature along thePlanckian locus may be stored in a look-up table within the luminaire orcalculated as needed from calibration parameters. To further improve thesimulation of an incandescent light source by the disclosed LEDluminaire further embodiments of the invention may also include a delayin the intensity control so as to simulate the thermal lag of anincandescent filament. When the power being supplied to an incandescentbulb is altered, the resultant light level emitted from the lamp doesn'timmediately change to follow the power change. Instead there is a slightdelay as the filament in the lamp either heats up or cools down until itreaches its new equilibrium. This delay, or thermal lag, is familiar tousers of incandescent products and appears natural, thus the very rapidcontrol of LED based luminaires, which follow power changes with almostno lag, can appear unnatural and mechanical. In the described inventionmeans are provided, either through software or through electricalcircuitry, to simulate this thermal lag by regulating the power suppliedto the LED emitters so as to mimic the heat up and cool down delay of anincandescent filament.

FIG. 12 illustrates the strobe and control zones of an embodiment of theinvention. In one embodiment of the invention the LED modules 106 arearranged in rings or control zones. FIG. 12 shows luminaire 210 withcontrol zones 212, 214 and 216. Although three control zones are hereinillustrated the invention is not so limited and any number and shape ofcontrol zones may be utilized. It is common in automated LED luminairesto provide a single strobe control channel for the entire luminaire suchthat varying speeds and styles of strobing may be selected for theluminaire. In one embodiment of the invention the luminaire is insteadprovided with a number of strobe control channels, one for each zone.Each of the control zones 212, 214 and 216 may be controlledindividually and independently of the other control zones. In particulara different strobe speed and style may be applied to each of the controlzones. These styles and speeds may further be coordinated such that apleasing overall effect is obtained automatically. Strobe styles may beselected from a list comprising but not limited to; simple strobe,snap-ramp strobe, ramp-snap strobe, ramp-ramp strobe, random strobe,flicker strobe and other strobe styles known in the art. In yet furtherembodiments the overall synchronization of control zones may becoordinated through an additional master strobe channel and associatedmacros.

In further embodiments the color and intensity of control zones 212,214, and/or 216 may be controlled individually and independently of theother control zones 212, 214, and/or 216. In such embodiments, adifferent color and intensity may be applied to each of the controlzones 212, 214, and 216. These colors and intensities may further becoordinated such that a pleasing effect is obtained automatically.Examples of the effects possible are rainbow effects, color chases, andcolor waves. In further embodiments these color and intensity effectsfor each control zone 212, 214, and 216 acting independently or insynchronization may be pre-programmed in the luminaire such that theoperator may recall a complete effect simply. In further embodiments acontrol channel is assigned to give the operator quick and direct accessto such pre-programmed effects.

While the disclosure has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments may be devised whichdo not depart from the scope of the disclosure as disclosed herein. Thedisclosure has been described in detail, it should be understood thatvarious changes, substitutions and alterations can be made heretowithout departing from the spirit and scope of the disclosure.

What is claimed is:
 1. A luminaire comprising: an array of LED modulesgenerating a directional light beam a first lenslet array a secondlenslet array coupled with a first non-zero transparency multi-celllouver mask which is array which can be moved along the light beam asecond multi-cell louver mask array where each cell is large enough tocontain the area bounded by a plurality of cells from the first louvermask.
 2. The luminaire of claim 1 wherein first louver mask is made ofplastic.
 3. The luminaire of claim 1 wherein the first louver mask ismade of glass.
 4. The luminaire of claim 1 wherein the first louver maskis more transparent than non-transparent.
 5. The luminaire of claim 1wherein first louver mask is close to full transparency.
 6. Theluminaire of claim 4 wherein second louver mask is non-transparent. 7.The luminaire of claim 4 wherein second louver mask is morenon-transparent than transparent.
 8. The luminaire of claim 4 whereinsecond louver mask is more transparent than non-transparent.
 9. Theluminaire of claim 4 wherein second louver mask is close to fulltransparency.
 10. The luminaire of claim 8 which further comprises athird louver mask which is large enough to bound the area of the secondmulti-louver mask.
 11. The luminaire of claim 9 wherein third louvermask is non-transparent.